1. Field of the Invention
The present invention relates to a vehicle-mounted unit mounted to an automobile for a toll collection system using radio communication.
2. Description of the Related Art
Toll collection systems for toll roads aiming to make toll payment cashless and allow toll gates at entrances and exits to be automated, as well as enabling nonstop passage, are conventionally known.
In such toll collection systems, in order to make the system cashless, any of a variety of cards such as a bank card or a prepaid card, or a credit card or an IC card recorded with information to identify the user must be inserted into a vehicle-mounted unit. In such cases, the card is inserted into the vehicle-mounted unit and if the information stored on the card is suitable, the card can be used.
FIG. 9 is a block diagram showing the functional configuration of a vehicle-mounted unit representing a conventional vehicle-mounted unit.
In the diagram, a central processing unit (CPU) 2 is disposed in a vehicle-mounted unit 1, controlling a radio wave detector portion 5, a communication control portion 6, a storage medium interface portion 4, a card insertion detector switch 13 being a storage medium insertion detector portion, a memory 7, and a display portion 14. Power is supplied to these portions from a power source (not shown). The radio wave detector portion 5 detects the strength of a radio signal from a road-side machine (not-shown) by means of an antenna 11. The communication control portion 6 sends and receives data to and from the road-side machine by radio by means of the antenna 11. The storage medium interface portion 4 sends and receives data to and from an IC card 20 which is a storage medium. The memory 7 stores the information necessary for toll collection between the road-side machine and the IC card 20. The display portion 14 serves the function of conveying information concerning the toll collection results to the driver, and may comprise, for example, light emitting diodes, a liquid-crystal display, a voice generating device, etc. A storage medium insertion portion 12 for the insertion of the IC card 20 is also disposed in the vehicle-mounted unit 1. When the IC card 20 is inserted into the storage medium insertion portion 12, the card insertion detector switch 13 being a storage medium insertion detector portion is switched on and the CPU 2 receives a storage medium insertion confirmation signal.
A memory 22 capable of recording and holding the information necessary for toll collection, and a vehicle-mounted unit interface portion 21 for exchanging data with the vehicle-mounted unit 1 are disposed on the IC card 20.
In a toll collection system, a toll collection suitability check is performed by confirming whether the IC card 20 is correctly inserted into the storage medium insertion portion 12 of the vehicle-mounted unit 1, and comparing the information, such as the user ID, the expiration date of the IC card 20, etc., stored in advance in the memory 22 of the IC card 20 with the information stored in the memory 7 of the vehicle-mounted unit 1 to confirm if the IC card 20 is suitable for toll collection.
Furthermore, the radio wave detector portion 5 detects the strength of the radio signal from the road-side machine and confirms whether the radio signal is strong enough to enable the transmission of toll collection data between the road-side machine and the communication control portion 6, and if data transmission is possible, sends a signal to the CPU 2 indicating that the vehicle is within a toll collection communication zone.
In this manner, once the vehicle is within a toll collection communication zone and a toll collection suitability check of the IC card 20 has been completed, toll collection is performed. Consequently, once the toll collection suitability check of the IC card 20 has been completed, toll collection is performed immediately if the vehicle proceeds into a toll collection communication zone.
However, in a conventional toll collection system, the vehicle may approach a toll gate without the IC card having been inserted into the vehicle-mounted unit 1 and the vehicle may already be within the toll collection communication zone before the driver notices that the IC card 20 has not been inserted. In that case, even if the IC card 20 is then inserted, a certain amount of time is required to perform a toll collection suitability check of the IC card 20 and prepare the IC card 20 for use. That is to say, the time required to perform the series of actions in the toll collection suitability check, namely, initializing the IC card 20, reading the information from the memory 22 of the IC card 20, and confirming that the IC card is suitable for toll collection, is sufficiently large compared to the time the vehicle passes through the toll collection communication zone that it cannot be ignored. Consequently, one problem has been the possibility of circumstances arising in which a toll cannot be collected in time within a toll collection communication zone.
For example, if the toll collection communication zone is 10 m long, and the speed of the vehicle is 10 kph, it only takes 3.6 seconds to pass through the toll collection communication zone. The time required for a toll collection suitability check of a storage medium such as the IC card 20 depends on the transmission rate of the storage medium interface portion 4, for example, in the case of the IC card 20, a minimum of about one second is required on the whole for the CPU 2 to verify that the card is correctly inserted and to perform a toll collection suitability check of the IC card.
For that reason, when insertion of the IC card is delayed, the toll cannot be collected within the toll collection communication zone. Furthermore, even if the IC card 20 is hurriedly inserted into the vehicle-mounted unit 1, concern that toll collection will not be performed may lead to confusion in the driver's mental state. In addition, measures are then required at the toll gate for cases where toll collection is not possible such as installing means for inhibiting further movement of a vehicle on which toll collection cannot be performed.
On the other hand, the vehicle-mounted unit for an information transmission device indicated in Japanese Patent Laid-Open 8-22594 is a known example of a conventional vehicle-mounted unit for a toll collection system capable of preventing delayed insertion of cards such as the IC card 20. The device alerts the driver to the fact that the card has not been inserted.
However, the device merely urges the driver to insert the card, and if the driver does not insert the card swiftly, the vehicle still passes through the toll collection communication zone and toll collection cannot be performed.